An acoustic emission is a generally nonaudible noise caused by minute changes in a material or object due to stresses imposed thereon. Thus, when a material undergoes a permanent plastic deformation, it will generate a sound which may be monitored by ultrasensitive means.
This phenomenon can be used, for example, to monitor nuclear reactor vessels for material and structural failures such as fuel rod cracks. Since the bulk of acoustic emissions are inaudible, it is necessary to detect them by means of transducers which are placed at various locations on the surface of the object or vessel to be tested. The more sensors which can be present, then the greater the likelihood of detecting and locating a material failure. Therefore, the range of response and the cost of each individual transducer becomes of prime importance. Presently available transducers of sufficient sensitivity, typically piezoelectric crystals, usually only provide a narrow band of frequency response to acoustic emissions and are relatively quite expensive.
It is therefore an object of this invention to provide a transducer device for detecting acoustic emissions from objects.
Another object of this invention is to provide an inexpensive broadband detector of acoustic emissions.
Another object of this invention is to provide a method for detecting acoustic emissions from objects.